At Ananka Fasteners Pvt Ltd, we engineer, manufacture, and supply premium SS 347 (UNS S34700) Heavy Hex Nut built for demanding service. Niobium-stabilised austenitic with excellent resistance to intergranular corrosion at high temperature. This technical datasheet covers the precise dimensional tolerances per ASME B18.2.2 and the material requirements dictated by ASTM A194 Gr 8C and ASTM A276 / A479.
A SS 347 Heavy Hex Nut provides a larger bearing surface and wrenching area than a standard hex nut, and is typically paired with heavy hex bolts and stud bolts in piping and pressure-boundary joints. The tables below provide the principal dimensions, equivalent material grades, chemical composition and mechanical properties covered by the technical data for this product.
Our heavy hex nuts are manufactured in standard and custom configurations, ensuring a precise fit for demanding structural, piping, and chemical-process applications.
| Product Name | SS 347 Heavy Hex Nut | Material Category | Stainless Steel |
| Material Grade | SS 347 (UNS S34700) | Fastener Spec | ASTM A194 Gr 8C |
| Dimension Spec | ASME B18.2.2 | Material Spec | ASTM A276 / A479 |
| Thread Standard | ASME B1.1 (UNC, UNF, 8UN) | Thread Tolerance | Class 2B / 3B (Internal) |
The ASME B18.2.2 specification governs the physical geometry of this product. The tolerances below ensure a secure, reliable mate under service loads. Heavy hex nuts provide a larger bearing surface and greater thickness for high-load joints.
| Nominal Size (in) | Width Across Flats (Max – Min) | Width Across Corners (Max) | Thickness (Max – Min) |
|---|---|---|---|
| 1/2″ | 0.875 – 0.850 | 1.010 | 0.504 – 0.464 |
| 5/8″ | 1.062 – 1.031 | 1.227 | 0.631 – 0.587 |
| 3/4″ | 1.250 – 1.212 | 1.443 | 0.758 – 0.710 |
| 7/8″ | 1.438 – 1.394 | 1.660 | 0.885 – 0.833 |
| 1″ | 1.625 – 1.575 | 1.876 | 1.012 – 0.956 |
| 1-1/8″ | 1.812 – 1.756 | 2.093 | 1.139 – 1.079 |
| 1-1/4″ | 2.000 – 1.938 | 2.309 | 1.251 – 1.187 |
The heavy hex nut thread is manufactured to match the corresponding heavy hex bolt or stud thread series and class. Buyers should confirm the required nominal size, thread series and thread class against the purchase drawing or applicable standard before ordering.
The UNS S34700 Heavy Hex Nut is manufactured from SS 347, a stainless steel. The equivalent designations below assist with cross-referencing this material against European, British and other national standards.
| US / UNS | Werkstoff Nr. (DIN) | European (EN) | British Standard (BS) | Other / AFNOR |
|---|---|---|---|---|
| S34700 | 1.4550 | X6CrNiNb18-10 | 347 S31 | Z6 CNNb 18-10 (AFNOR) |
This section details the chemical composition limits and minimum mechanical properties governing SS 347 (UNS S34700) fasteners, as dictated by ASTM A194 Gr 8C (chemistry & mechanicals) and the raw bar/rod standard ASTM A276 / A479.
| Element | Composition, % |
|---|---|
| Chromium | 17.0–19.0 |
| Nickel | 9.0–13.0 |
| Niobium (Nb+Ta) | 10×C–1.0 |
| Carbon, max | 0.08 |
| Manganese, max | 2.0 |
| Silicon, max | 0.75 |
| Phosphorus, max | 0.045 |
| Iron | Balance |
| Condition / Temper | Tensile Strength min, psi (MPa) | Yield Strength min, psi (MPa) | Elongation min, % | Hardness |
|---|---|---|---|---|
| Annealed bar | 75 000 (515) | 30 000 (205) | 40 | – |
Our SS 347 heavy hex nuts are specified across the following industries and service conditions, drawing on the material’s core strengths:
For applications exposed to highly aggressive chemicals or chloride-rich environments, the exact operating conditions should be reviewed against the certified data for this grade rather than general stainless steel assumptions.
Every batch of Heavy Hex Nuts produced undergoes rigorous internal and third-party testing to ensure zero-defect delivery. We supply complete traceability with our global shipments.
For technical documentation and quotations, buyers can also review the Ananka Fasteners manufacturing and supply range or contact the team through the fastener enquiry and technical support page.
This datasheet references ASME B18.2.2 for dimensional requirements and ASTM A194 Gr 8C for material and fastener requirements. The applicable standard edition and purchase requirements should be confirmed for every project.
For ASME standards information, see the ASME standards catalogue. For ASTM International material and fastener specifications, see the ASTM International standards catalogue. These external references are provided for standards identification; the purchaser should verify the current edition applicable to the order.
A SS 347 Heavy Hex Nut is a heavy-series hex nut with a larger width-across-flats than a standard hex nut manufactured from SS 347 (UNS S34700). The product combines the ASME B18.2.2 dimensional geometry with the ASTM A194 Gr 8C material and fastener requirements.
The dimensional information in this datasheet is based on ASME B18.2.2, which governs the physical geometry of this product. The table above provides the principal dimensions listed for the SS 347 product range.
SS 347 is identified as UNS S34700. The equivalent designations listed in this datasheet include Werkstoff Nr. 1.4550, EN X6CrNiNb18-10, British Standard 347 S31, Z6 CNNb 18-10 (AFNOR).
SS 347 is a stainless steel known for good general corrosion resistance and wide industrial availability. For applications exposed to highly aggressive chemicals or chloride-rich environments, the exact operating conditions should be reviewed against the certified data for this grade rather than general stainless steel assumptions.
The product information supports standard and custom configurations. For a quotation, provide the required material grade, nominal size, dimensional requirement, quantity, standard and any inspection or certificate requirements.
Need a SS 347 Heavy Hex Nut for an industrial project? Send the required size, quantity, standard and certification requirements to Ananka Fasteners. Our team can review the requirement and provide technical and commercial information for standard or custom configurations.
Recommended RFQ details: SS 347 / UNS S34700, nominal size, ASME B18.2.2 requirement, quantity, inspection requirements and EN 10204 certificate requirements where applicable.
